High-efficiency modular uninterruptible power supply

ABSTRACT

Examples of the disclosure include a power system comprising an input to receive input power, an output to provide power to a load, a sensor configured to provide load information indicative of power drawn by the load, a plurality of power modules, each having a power module input configured to be coupled to the input, and a power module output configured to be coupled to the output, and a controller coupled to the power modules and the sensor, and being configured to control the power modules to provide power to the output, receive the load information from the sensor, select, based on the load information, at least one power module to maintain in an active state to provide power to the output, and deactivate each power module other than the at least one power module based on selecting the at least one power module to maintain in the active state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 120 as a continuationof U.S. application Ser. No. 17/115,117, titled “HIGH-EFFICIENCY MODULARUNINTERRUPTIBLE POWER SUPPLY,” filed on Dec. 8, 2020, which is herebyincorporated by reference in its entirety.

BACKGROUND 1. Field of the Disclosure

At least one example in accordance with the present disclosure relatesgenerally to increasing an efficiency of a power device.

2. Discussion of Related Art

The use of power devices, such as Uninterruptible Power Supplies (UPSs),to provide regulated, uninterrupted power for sensitive and/or criticalloads, such as computer systems and other data processing systems, isknown. Certain UPSs may be “modular,” in that power modules may be addedto or removed from the UPS to increase or decrease a maximum poweroutput of the UPS, respectively.

SUMMARY

According to at least one aspect of the present disclosure, a powersystem is provided comprising an input to receive input power, an outputto provide output power to a load, a sensor configured to provide loadinformation indicative of power drawn by the load, a plurality of powermodules, each power module of the plurality of power modules having apower module input configured to be coupled to the input, and a powermodule output configured to be coupled to the output, and a systemcontroller coupled to the plurality of power modules and to the sensor,the system controller being configured to control the plurality of powermodules to provide power to the output, receive the load informationfrom the sensor, select, based on the load information, at least onepower module of the plurality of power modules to maintain in an activestate to provide power to the output, and deactivate each power moduleof the plurality of power modules other than the at least one powermodule based on selecting the at least one power module to maintain inthe active state.

In various examples, each power module of the plurality of power modulesincludes a module sensor configured to determine module load informationindicative of power provided at a respective power module output, and amodule controller configured to receive the module load information fromthe module sensor. In some examples, each activated module controller isconfigured to detect, based on the module load information, an overloadcondition, and provide an activation signal to at least one other powermodule of the plurality of power modules based on detecting the overloadcondition. In at least one example, each activated module controller iscommunicatively coupled to the system controller and is configured toreceive, from the system controller, a deactivation signal or anactivation signal, control the respective power module to continueproviding module output power responsive to receiving the activationsignal, and control the respective power module to deactivate anddiscontinue providing module output power responsive to receiving thedeactivation signal.

In various examples, the system controller is configured to select afirst group of one or more power modules to maintain in an active stateresponsive to the overload condition, provide the activation signal toeach power module in the first group of one or more power modules,select a second group of one or more power modules to deactivateresponsive to the overload condition, and provide the deactivationsignal to each power module in the second group of one or more powermodules. In some examples, selecting the first group of one or morepower modules to maintain in the active state includes identifying amost efficient group of one or more power modules to satisfy theoverload condition. In at least one example, the system controller isconfigured to detect, based on the load information, an overloadcondition, activate each deactivated power module of the plurality ofpower modules to provide module output power based on detecting theoverload condition.

In various examples, the system controller is configured to select afirst group of one or more power modules to maintain in an active stateresponsive to the overload condition, provide the activation signal toeach power module in the first group of one or more power modules,select a second group of one or more power modules to deactivateresponsive to the overload condition, and provide the deactivationsignal to each power module in the second group of one or more powermodules. In some examples, selecting the first group of one or morepower modules to maintain in the active state includes identifying amost efficient group of one or more power modules to satisfy theoverload condition. In at least one example, deactivating each powermodule includes sending a deactivation signal to each power module.

In various examples, each power module includes a respective switchconfigured to control output electrical power, and each power module isconfigured to deactivate the switch responsive to receiving thedeactivation signal. In some examples, each power module includes aninverter including the respective switch. In at least one example, eachpower module includes a power bus coupled to the inverter, and eachpower module is configured to maintain the power bus at an activeoperating voltage level while deactivated.

According to at least one example of the disclosure, a power module in apower system providing power to a load is provided, the power modulecomprising a module input configured to receive input power, a moduleoutput configured to provide output power to the load, at least onemodule sensor configured to provide load information indicative of theoutput power provided at the module output, and a module controllercoupled to the at least one module sensor and configured to receive theload information from the at least one module sensor, determine, basedon the load information, that an overload condition exists, provide,responsive to determining that the overload condition exists, anactivation signal to at least one other power module instructing the atleast one other power module to provide output power to the load,determine that the power module is to be deactivated, and deactivate thepower module to discontinue providing the output power to the moduleoutput.

In various examples, determining that the overload condition includesdetermining, based on the load information, that a power rating of theload exceeds a power level of power provided to the load. In someexamples, the module controller is further configured to receive anactivation signal from the at least one other power module, andtransition from deactive to active responsive to receiving theactivation signal from the at least one other power module. In at leastone example, the module controller is coupled to a system controllercoupled to the at least one other power module, and wherein determiningthat the power module is to be deactivated includes receiving adeactivation signal from the system controller.

In various examples, the power module further comprises an inverterincluding at least one switching device to control the output power, anddeactivating the power module includes deactivating the at least oneswitch. In some examples, the power module further comprises a power busbetween the module input and the inverter, and the power module isconfigured to maintain the power bus at an active operating voltagelevel while deactivated.

According to at least one example, a non-transitory computer-readablemedium storing thereon sequences of computer-executable instructions forcontrolling a plurality of power modules is provided, the sequences ofcomputer-executable instructions including instructions that instruct atleast one processor to control the plurality of power modules to providepower to the output, receive load information indicative of a powerdrawn by a load from a load sensor, select, based on the loadinformation, at least one power module of the plurality of power modulesto maintain in an active state to provide power to the output, anddeactivate each power module of the plurality of power modules otherthan the at least one power module based on selecting the at least onepower module to maintain in the active state.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of at least one embodiment are discussed below withreference to the accompanying figures, which are not intended to bedrawn to scale. The figures are included to provide an illustration anda further understanding of the various aspects and embodiments, and areincorporated in and constitute a part of this specification, but are notintended as a definition of the limits of any particular embodiment. Thedrawings, together with the remainder of the specification, serve toexplain principles and operations of the described and claimed aspectsand embodiments. In the figures, each identical or nearly identicalcomponent that is illustrated in various figures is represented by alike numeral. For purposes of clarity, not every component may belabeled in every figure. In the figures:

FIG. 1 illustrates a block diagram of a power system according to anexample;

FIG. 2 illustrates a block diagram of a power module according to anexample;

FIG. 3 illustrates a process of controlling a power system according toan example; and

FIG. 4 illustrates a process of controlling a power system according toanother example.

DETAILED DESCRIPTION

Examples of the methods and systems discussed herein are not limited inapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in theaccompanying drawings. The methods and systems are capable ofimplementation in other embodiments and of being practiced or of beingcarried out in various ways. Examples of specific implementations areprovided herein for illustrative purposes only and are not intended tobe limiting. In particular, acts, components, elements and featuresdiscussed in connection with any one or more examples are not intendedto be excluded from a similar role in any other examples.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Any references toexamples, embodiments, components, elements or acts of the systems andmethods herein referred to in the singular may also embrace embodimentsincluding a plurality, and any references in plural to any embodiment,component, element or act herein may also embrace embodiments includingonly a singularity. References in the singular or plural form are notintended to limit the presently disclosed systems or methods, theircomponents, acts, or elements. The use herein of “including,”“comprising,” “having,” “containing,” “involving,” and variationsthereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items.

References to “or” may be construed as inclusive so that any termsdescribed using “or” may indicate any of a single, more than one, andall of the described terms. In addition, in the event of inconsistentusages of terms between this document and documents incorporated hereinby reference, the term usage in the incorporated features issupplementary to that of this document; for irreconcilable differences,the term usage in this document controls.

As discussed above, uninterruptible power supplies (UPSs) are capable ofproviding uninterrupted power to certain loads. A modular UPS mayinclude a configurable number of power modules, which may be added to orremoved from the UPS to increase or decrease a maximum power output ofthe UPS, respectively. Each power module may have a respective poweroutput rating, and a total power output rating of the modular UPS may bedetermined based on the sum of the active power modules' power outputratings. For example, a modular UPS having two active power modules,each having a respective power rating of 5 kW, may have an output powerrating of approximately 10 kW, which is the sum of the modules' powerratings.

A power module may not operate at maximum capacity at all times. Forexample, a power module having a power rating of 5 kW may provide outputpower of any magnitude between 0 kW and 5 kW throughout the powermodule's lifecycle. In some examples, however, a power module may berestricted to operate within a certain range of power, such as within20% to 95% of the power module's power rating. In this example, a powermodule having a power rating of 5 kW would therefore be restricted tooutputting power between 1 kW and 4.75 kW. In other examples, any otherrange of power output values may be implemented, including 0% and 100%of a power module's power rating.

An efficiency of a power module may vary based on an output power of thepower module compared to the power module's output power rating. Forexample, a 5 kW power module providing 1 kW of output power (thusoperating at 20% of a rated output power) may operate less efficientlythan when the power module provides 3.25 kW of output power (thusoperating at 65% of a rated output power). Each power module may beassociated with power module efficiency information indicating acorresponding efficiency for each level of output power, where a peakefficiency may be achieved at an output power value between a minimumoutput power value (for example, 20% of a rated output power) and amaximum output power value (for example, 95% of a rated output power)for some power modules. In some examples, the power module efficiencyinformation may be stored as computer-readable information such that anelectrical device having access to the information is capable ofdetermining an efficiency of the power based on a load on the powermodule.

In a modular UPS having multiple power modules, it may be possible tosatisfy a load demand with multiple different combinations of activepower modules. For example, consider a modular UPS having three powermodules, each rated at 5 kW, the modular UPS being connected to a loaddemanding 3 kW of power. In one example, all three of the power modulescould provide 1 kW of output power each to satisfy the load's demand fora total of 3 kW of output power. In another example, two of the powermodules could provide 1.5 kW of output power each to satisfy the load'sdemand for a total of 3 kW of output power, and the third power modulecould provide no output power. In yet another example, a single one ofthe power modules could provide 3 kW of output power to satisfy theload's demand for 3 kW of output power, and the remaining two powermodules could provide no output power. In other examples, othercombinations of power modules could be implemented with each powermodule providing an amount of output power that may be the same ordifferent than that provided by other modules.

The efficiencies of the power modules in each of these examples maydiffer from one another. For example, a power module operating at oneload (for example, 20% of a rated load) may have an efficiency thatdiffers from an efficiency of the power module at a second load (forexample, 50% of a rated load). Furthermore, electrical losses of thepower module while the power module is active (for example, total activeand reactive losses) may differ from electrical losses of the powermodule while the power module is not active. Accordingly, it may beadvantageous to identify a most efficient combination of power modulesto satisfy a load's demand such that a total efficiency of a modular UPSsystem may be maximized.

Examples are provided for increasing an efficiency of a modular UPS byselectively activating power modules in a UPS. Load information isdetermined by a system controller, and/or a module controller in one ormore power modules to identify output power requirements of a load. Adetermination is made by the system controller as to which combinationof power modules can most efficiently satisfy the output powerrequirements. The identified combination of power modules is instructedby the system controller to maintain an active state in which outputpower is provided to the load. The remaining power modules areinstructed to enter a deactivated state in which the power modules donot provide output power to a load. For example, a deactivated powermodule may deactivate its inverter such that the output of the powermodule is disconnected from a power source of the power module.

The output power requirements of the load may change over time. Thesystem and/or module controllers may repeatedly re-evaluate whether awake-up condition is met, which may be based on the output powerrequirements. The wake-up condition may be that the output powerrequirements exceed the power rating of the combination of activatedpower modules, for example, or that the output power requirements havechanged above a threshold amount. If the wake-up condition is met, everypower module that was not already active (that is, the deactivated powermodules) may be activated by the system and/or module controllers toprovide output power to the load. The system controller again determinesa combination of power modules that can most efficiently satisfy theoutput power requirements of the load, and deactivates the remainingpower modules.

Current modular power systems, such as modular uninterruptible powersupplies, may maintain all power modules therein in an active state atall, or substantially all, times that the modular power system isactive. Such modular power systems may operate inefficiently, becauseeach power module may not be operating at or near its peak efficiencyand one or more power modules may be unnecessarily active. This is atechnical problem. An exemplary embodiment of a modular power system maycomprise an input to receive input power, an output to provide outputpower to a load, a sensor configured to provide load informationindicative of power drawn by the load, a plurality of power modules,each power module of the plurality of power modules having a powermodule input configured to be coupled to the input, and a power moduleoutput configured to be coupled to the output, and a system controllercoupled to the plurality of power modules and to the sensor. In someexamples, the system controller is configured to control the pluralityof power modules to provide power to the output, receive the loadinformation from the sensor, select, based on the load information, atleast one power module of the plurality of power modules to maintain inan active state to provide power to the output, and deactivate eachpower module of the plurality of power modules other than the at leastone power module based on selecting the at least one power module tomaintain in the active state. At least this foregoing combination offeatures comprises a modular power system that serves as a technicalsolution to the foregoing technical problem. This technical solution isnot routine and is unconventional. This technical solution is apractical application of the power system design that solves theforegoing technical problem and constitutes an improvement in thetechnical field of power supply design at least by increasing anefficiency of a power supply system.

FIG. 1 illustrates a block diagram of a power system 100 according to anexample. In some examples, the power system 100, or components thereof,may be or include a UPS, such as a modular UPS. The power system 100includes a power input 102, one or more energy storage devices 104, anarbitrary number of power modules 106, an output 108, a systemcontroller 110, and one or more system sensors 112. In some examples,the one or more energy storage devices 104 may not be external to, butmay be electrically and communicatively coupled to, the power system100. In one example, the power system 100 may be coupled to a load 114via the output 108. The system controller 110 includes a storage 116capable of storing computer-readable information. In some examples, thestorage 116 may be internal to the system controller 110, whereas inother examples, the storage 116 may be partially or entirely external tothe system controller 110, and may further be partially or entirelyinternal or external to the power system 100, albeit communicativelycoupled to the system controller 110.

The power input 102 is coupled to each of the power modules 106, and isconfigured to be coupled to a power source (not illustrated). Forexample, the power input 102 may be coupled to a utility mains powersupply, which may be an AC power supply. In other examples, the powerinput 102 may be connected to a DC power supply. The energy storagedevices 104 are coupled to the power modules 106, and arecommunicatively coupled to the system controller 110. As discussedabove, the one or more energy storage devices 104 may be external to thepower system 100, but may be electrically coupled to the power modules106 and communicatively coupled to the system controller 110. The powermodules 106 are coupled to the power input 102, the energy storagedevices 104, and the output 108, and are communicatively coupled to thesystem controller 110. In some examples, the power modules 106 arecommunicatively connected to each other. The output 108 is coupled tothe power modules 106 and is configured to be coupled to the load 114.

The system controller 110 is communicatively coupled to the energystorage devices 104, the power modules 106, and the system sensors 112.The system sensors 112 are communicatively coupled to the systemcontroller 110, and may be coupled to one or more additional components.For example, the system sensors 112 may include one or more temperature,voltage, current, and/or power sensors configured to sense temperature,voltage, current, and/or power information at any of the components102-108, including load information at the output 108 indicative ofoutput power drawn by the load 114 and/or power requirements of the load114. The load 114 is configured to be coupled to the power system 100via the output 108. The storage 116 is configured to be communicativelycoupled to the system controller 110, and may store computer-readableinformation such as load information, power module efficiencyinformation, and so forth.

The system controller 110 may control the power system 100 to operate inone of at least two modes of operation, including a normal mode ofoperation and a backup mode of operation, based on information receivedfrom the system sensors 112. For example, the system sensors 112 maysense input power information (for example, voltage and/or currentinformation) indicative of input power received at the power input 102and provide the input power information to the system controller 110,and/or may sense a temperature value indicative of an ambienttemperature in or near one or more components of the power system 100and provide the temperature information to the system controller 110. Ifthe system controller 110 determines that the input power is acceptable(for example, by having a voltage level within a range of acceptablevoltage levels), then the system controller 110 may control the powersystem 100 to be in the normal mode of operation. Otherwise, if thesystem controller 110 determines that the input power is not acceptable,then the system controller 110 may control the power system 100 to be inthe backup mode of operation.

In the normal mode of operation, power received at the power input 102is distributed to the power modules 106. As discussed in greater detailbelow, some or all of the power modules 106 may be in an active mode ofoperation. In the active mode of operation, a power module conditionsthe power received from the power input 102 and provides output power tothe output 108. A power module may also provide power to the energystorage devices 104 to charge the energy storage devices 104 during thenormal mode of operation.

In the backup mode of operation, power stored in the energy storagedevices 104 is distributed to the power modules 106. Power modules inthe active mode of operation may condition the power received from theenergy storage devices 104 and provide output power to the output 108.

In both the normal and backup mode of operation, the output 108 mayreceive power from the power modules 106 and provide the power to theload 114. In some examples, the output 108 may include or be connectedto one or more power distribution units (PDUs) to distribute power toone or more loads. For example, the load 114 may include multipledifferent loads, or the load 114 may be one of several loads receivingpower from the output 108.

As discussed above, in some examples, some of the power modules 106 maybe active and some of the power modules 106 may be inactive. In theactive mode, a power module provides output power to the output 108. Forexample, the output power may be derived from input power received fromone or both of the power input 102 or the energy storage devices 104. Inthe inactive mode, a power module does not provide output power to theoutput 108. As used herein, a “deactivated power module,” “inactivepower module,” or a power module that has been “deactivated” or“inactivated” refers to a power module that is not providing outputpower to the output 108. However, even in the inactive mode, a powermodule may still receive power from the power input 102 and/or mayprovide or receive power to or from the energy storage devices 104.Furthermore, certain components of a deactivated power module may remainoperational including, for example, a module controller of the powermodule, a rectifier of the module, and/or a DC/DC converter of themodule, as discussed in greater detail below.

FIG. 2 illustrates a block diagram of a power module 106 according to anexample. The power module 106 may be an example of any of the powermodules 106 of FIG. 1. The power module 106 includes a module input 202,a rectifier 204, a DC bus 206, an inverter 208, a module output 210, aDC/DC converter 212, an energy storage device power interface 214, amodule controller 216, and one or more module sensors 218. The rectifier204 includes one or more rectifier switches 220, the inverter 208includes one or more inverter switches 222, and the DC/DC converter 212includes one or more converter switches 224. The DC bus 206 includes oneor more bus capacitors 226.

The module input 202 is coupled to the rectifier 204, and is configuredto be coupled to the power input 102. The rectifier 204 is coupled tothe module input 202 and the DC bus 206. The DC bus 206 is coupled tothe rectifier 204, the inverter 208, and the DC/DC converter 212. Theinverter 208 is coupled to the DC bus 206 and to the module output 210.The module output 210 is coupled to the inverter 208 and the output 108.The DC/DC converter 212 is coupled to the DC bus 206 and to the energystorage device power interface 214. The energy storage device powerinterface 214 is coupled to the DC/DC converter 212, and is configuredto be coupled to the energy storage devices 104. The module controller216 is communicatively coupled to the module sensors 218 and to theswitches 220-224. In some examples, the module controller 216 mayfurther be communicatively coupled to the system controller 110 and/orto one or more other module controllers of one or more other powermodules 106. The module sensors 218 are communicatively coupled to themodule controller 216, and may be coupled to one or more additionalcomponents. For example, the module sensors 218 may include one or moretemperature, voltage, current, and/or power sensors configured to sensetemperature, voltage, current, and/or power information at any of thecomponents 202-214, including load information at the module output 210indicative of output power provided at the module output 210, powerrequirements of the load 114, and/or a voltage at the module output 210.The rectifier switches 204 are communicatively coupled to the modulecontroller 216. The inverter switches 222 are communicatively coupled tothe module controller 216. The converter switches 224 arecommunicatively coupled to the module controller 216.

In the normal mode of operation of the power system 100, the powermodule 106 is configured to receive input power from the power input 102at the module input 202. In one example, the input power is AC power.The rectifier 204 is configured to rectify the AC power to DC power. Forexample, the module controller 216 may control the rectifier switches220 to rectify the AC power to DC power. The DC power is provided to theDC bus 206.

The DC bus 206 conducts DC power to the inverter 208 and/or DC/DCconverter 212, and to the bus capacitors 226. The bus capacitors 226receive the DC power to maintain the DC bus 206 at a desired voltagelevel, which may be referred to herein as an “active operating voltagelevel.” As understood by those of ordinary skill, it may be advantageousto maintain a DC bus from which an inverter receives electrical power ata certain voltage level for the inverter to convert power receivedtherefrom to AC power.

DC power received from the rectifier 204 may be provided to the inverter208 and/or the DC/DC converter 212. For example, if the power module 106is in an active mode of operation in which the inverter 208 inverts DCpower to AC power and provides the AC power to the module output 210,then the module controller 216 may control the inverter switches 222such that the inverter 208 receives and inverts DC power stored by thebus capacitors 226 from the DC bus 206. However, in examples in whichthe bus capacitors 226 are maintained at the active operating voltagelevel even when the inverter 208 is not inverting power, the powermodule 106 may be able to quickly respond to a change in operation inwhich the inverter 208 does begin inverting power, because the voltagelevel on the DC bus 206 is already maintained at the active operatingvoltage level by the bus capacitors 226. Thus, the bus capacitors 226need not be recharged from a discharged state, where such recharging mayotherwise take a longer amount of time than if the bus capacitors 226are already charged. The module controller 216 may therefore control theinverter 208 to provide output power to the output 108 via the moduleoutput 210 when the power module 106 is in the active mode of operation,where the power module 106 is able to quickly respond to a transitionfrom a deactive to active mode of operation.

The module controller 216 may alternately or additionally control theconverter switches 224 such that the DC/DC converter 212 receives andconverts DC power from the DC bus 206, and provides the converted powerto the energy storage device power interface 214. For example, the DC/DCconverter 212 may provide DC power to the energy storage device powerinterface 214 to charge one or more of the energy storage devices 104connected thereto. In some examples, the DC/DC converter 212 may chargethe energy storage devices 104 when the power module 106 is in eitherthe active or inactive mode of operation. For example, the energystorage devices 104 may include one or more batteries, capacitors,flywheels, or other rechargeable energy storage devices capable of beingrecharged via the DC/DC converter 212.

In the backup mode of operation of the power system 100, the powermodule 106 does not receive power at the module input 202. The powermodule 106 may receive DC power from the energy storage devices 104 atthe energy storage device power interface 214. Power received from theenergy storage device power interface 214 is provided to the DC/DCconverter 212. The module controller 216 may control the converterswitches 224 to convert power received from the energy storage devicepower interface 214 to DC power of a different voltage level, andprovide the converted power to the DC bus 206. The DC bus 206 mayconduct the received power to the inverter 208 and/or the bus capacitors226. As discussed above, if the power module 106 is in an active mode ofoperation, then the module controller 216 may control the inverterswitches 222 to draw power via the DC bus 206 and provide invertedoutput power to the module output 210. Otherwise, the inverter 208 maynot draw any appreciable power from the DC bus 206 if the power module106 is in the deactive mode of operation.

Accordingly, the power system 100 may operate at least in a normal modeof operation or a backup mode of operation. In the normal and/or thebackup modes of operation, each power module 106 may be in either anactive mode or a deactive mode. For power modules in an active mode,power received from the power input 102 and/or the energy storagedevices 104 (depending on whether the power system 100 is in a normal orbackup mode of operation) may be provided to the output 108 via themodule output 210 of a respective power module 106. Otherwise, if apower module 106 is in an inactive mode, the power module 106 may notprovide power to the module output 210 and, consequently, the output108. However, even in the inactive mode, components of the power module106 may remain operational, including one or more of the rectifier 204,the DCDC converter 212, the module controller 216, and/or the modulesensors 218. The module controller 216 may control the power module 106to draw power from the power input 102 and/or the energy storage devices104 to maintain the bus capacitors 226 at an active operating voltagelevel, such that the power module 106 is able to quickly respond to aninstruction to provide output power. For example, the module controller216 may control the rectifier 204 to draw power from the module input202 and/or may control the DC/DC converter 212 to draw power from, orprovide power to, the energy storage device power interface 214.Furthermore, a deactivated power module may monitor load information ata respective module output 210.

Operation of the power system 100 will now be discussed with respect toFIGS. 3 and 4. FIG. 3 illustrates a process 300 of operating the powersystem 100 according to an example. The process 300 may be executed inconnection with one or more components of the power system 100,including the system controller 110. FIG. 4 illustrates a process 400 ofoperating the power system 100 according to another example. The process400 may be executed in connection with one or more components of thepower system 100, including a respective module controller 216 of one ormore of the power modules 106. In some examples, the processes 300, 400may both be executed by the power system 100, including by executing theprocesses 300, 400 simultaneously.

At act 302, the process 300 begins. For example, the process 300 maybegin at a system start-up of the power system 100, or at another timethereafter. As discussed in greater detail below, acts of the process300 may be executed repeatedly and, in some examples, indefinitely.

At act 304, the system controller 110 controls one or more of the powermodules 106 to provide power to the output 108. The system controller110 may control fewer than all of the power modules 106 to provide powerto the output 108, or may control all of the power modules 106 toprovide power to the output 108. For example, the system controller 110may control all of the power modules 106 to provide power to the output108 when the process 300 and act 304 are first executed before a moreefficient subset of the power modules 106 is identified, in examples inwhich such a subset is identified, as discussed in greater detail below.

Controlling the one or more of the power modules 106 to provide power tothe output 108 may include sending an activation signal from the systemcontroller 110 to each of the one or more power modules 106 to providepower (also referred to herein as “activating” the one or more powermodules 106). The activation signal may be sent from the systemcontroller 110 to a respective module controller 216. The modulecontroller 216, in turn, may control the respective components of thepower module 106 to provide power to the module output 210, such as bycontrolling the switches 220-224 to provide power to the module output210. Controlling the switches 220-224 to provide power to the moduleoutput 210 may include controlling the inverter switches 222 to draw DCpower from the bus capacitors 226, invert the DC power to AC power, andprovide the AC power to the module output 210. In other examples, act304 may include the system controller 110 directly controlling thecomponents of the power module 106, including the inverter switches 222,to provide power to the module output 210.

At act 306, the system controller 110 monitors the load 114. Forexample, the system controller 110 may monitor the load 114 to determineload information indicative of a power drawn by the load 114 at theoutput 108, and power requirements of the load 114. The systemcontroller 110 may determine the load information based on informationsensed by the system sensors 112, including information sensed at theoutput 108. For example, the system sensors 112 may include one or morecurrent or voltage sensors configured to sense a current and/or voltageat the output 108, and/or at an output of each of the power modules 106.The system sensors 112 may provide the load information to the systemcontroller 110. In other examples, the power module 106 may provide theload information to the system controller 110, where a respective modulecontroller 216 of a power module 106 may obtain module load informationby polling the module sensors 218, and send the module load informationto the system controller 110.

At act 308, the system controller 110 determines whether additionalpower modules should be activated. For example, the system controller110 may determine that additional power modules should be activatedwhere an “overload condition” is detected. An overload condition may bedetected where the output power requirements of the load 114 increasebeyond the output power capacity of the power modules 106 that arecontrolled to provide output power at act 304. Such an overloadcondition may be indicated by certain electrical parameters (forexample, an output current, voltage, and/or power) falling outside of anacceptable range or ranges of values, such as a sub-cycle disturbance inoutput power provided to the load 114, or an amount of current providedto the load 114 being greater than a rated maximum output current of thepower modules 106, or another example of a disturbance in electricalparameters. It may be desirable to activate additional power modules tomeet the output power requirements if an overload condition is detected.In other examples, the system controller 110 may determine that anoverload condition exists even if the power modules 106 that arecontrolled to provide output power at act 304 are capable of meeting theincreased output power requirements of the load 114. For example, thesystem controller 110 may detect an overload condition in such ascenario where the system controller 110 determines that activatingadditional power modules would nonetheless be desirable becauseactivating additional power modules would increase an efficiency of thepower system 100.

If the system controller 110 determines that additional power modules106 should not be activated (308 NO), then the process 300 returns toact 306. The system controller 110 resumes monitoring the load 114, andacts 306 and 308 are repeated until a determination is made thatadditional power modules 106 should be activated. For example, if thesystem controller 110 detects an overload condition and determines thatadditional power modules 106 should be activated (308 YES), then theprocess 300 continues to act 310.

At act 310, the system controller 110 activates any of the power modules106 that are deactivated. Deactivated power modules may include those ofthe power modules 106 that are not controlled to provide output power tothe output 108 at act 304. Activating the power modules 106 at act 310may be similar to act 304. For example, the system controller 110 maysend an activation signal to each of the power modules 106 that isdeactivated, and a corresponding module controller 216 may control thepower module 106 to provide output power to the output 108 responsive toreceiving the activation signal. Once each of the power modules 106 hasbeen activated, the power modules 106 collectively provide power to theoutput 108 at a first efficiency.

At act 312, the system controller 110 selects at least one power moduleof the power modules 106 to maintain in an active state based on theload information received at act 306. The at least one power module willprovide power to the output 108 at a second efficiency, which may bedifferent than the first efficiency if the at least one power moduleincludes fewer than all of the power modules 106. In various examples,the system controller 110 may select the at least one module such thatthe at least one module is capable of meeting the output powerrequirements of the load, and such that the second efficiency is greaterthan the first efficiency. In some examples, therefore, the systemcontroller 110 determines a most efficient group of the power modules106 capable of meeting output power requirements, or at least determinesa group of power modules 106 capable of meeting the output powerrequirements with a greater efficiency than if all of the power modules106 were maintained in an active state.

In some examples, the system controller 110 may access stored efficiencyinformation indicative of an efficiency of each of the power modules106. For example, the efficiency information may be accessibly stored inthe storage 116. The efficiency information may indicate a powerefficiency of the power module 106 against a load on the power module106. For example, the efficiency information may indicate a firstefficiency where the power module 106 is providing 25% of a rated load,a second efficiency where the power module 106 is providing 50% of arated load, a third efficiency where the power module 106 is providing75% of a rated load, and so forth. Act 312 may include using theefficiency information to determine a most efficient group of the powermodules 106 that is capable of satisfying the output load requirements.For example, the system controller 110 may determine that the outputpower requirements of the load 114 could be satisfied by four of thepower modules 106 operating at 45% of a rated load, three of the powermodules 106 operating at 60% of a rated load, or two of the powermodules 106 operating at 90% of a rated load. The system controller 110may then use the efficiency information to determine which number andcombination of the power modules 106 is most appropriate, and selectthese power modules to remain active at act 312.

At act 314, the system controller 110 deactivates those of the powermodules 106 that are not remaining active. Deactivating the powermodules 106 may include sending, by the system controller 110, adeactivation signal to each of the power modules 106 not remainingactive, or may include de-asserting an activation signal that the systemcontroller 110 previously sent to the power modules 106. The powermodules 106 discontinue providing output power to the output 108responsive to receiving the deactivation signal. A respective modulecontroller 216 may receive the deactivation signal and, in responsethereto, control components thereof, such as the switches 220-224, todiscontinue providing power to the module output 210. For example, themodule controller 216 may control the inverter switches 222 todiscontinue providing output power at the module output 210 (alsoreferred to herein as “deactivating the inverter 208”), which mayinclude controlling one or more of the inverter switches 222 to be in anopen and non-conducting position, such that the DC bus 206 iselectrically disconnected form the module output 210. In other examples,deactivating the power modules 106 may include the system controller 110directly controlling components of the power modules 106, such as one ormore of the switches 220-224, to discontinue providing output power atthe module output 210. In various examples, certain components of thepower module 106, including the module controller 216 and the sensors218, remain operational even where the power module 106 is in a deactivemode.

The process 300 then returns to act 304. At act 304, the systemcontroller 110 controls those of the power modules 106 selected toremain active at act 312 to provide output power at the output 108.Those of the power modules 106 that are deactivated may not becontrolled to provide output power at the output 108, such as bydeactivating the inverter 208 thereof. However, those of the powermodules 106 that are deactivated may be controlled to perform certainoperations, such as monitoring module load information at the moduleoutput 210 using the module sensors 218. A respective module controller216 of a deactivated power module may also control the power module todraw power from the module input 202 or the energy storage device powerinterface 214 to maintain the bus capacitors 226 at an active operatingvoltage level, as discussed above.

A respective module controller 216 of a deactivated power module mayalso control the power module to provide a charging current to theenergy storage devices 104 via the energy storage device power interface214. For example, the module controller 216 may control the switches220, 224 to draw AC power from the module input 202, rectify the ACpower to DC power, provide the DC power to the DC bus 206, draw the DCpower from the DC bus, convert the DC power to converted DC power, andprovide the converted DC power to the energy storage device 104 via theenergy storage device power interface 214. In other examples, adeactivated power module may not provide output power via the energystorage device power interface 214.

Turning to FIG. 4, at act 402, the process 400 begins. For example, theprocess 400 may begin at a system start-up of the power system 100, orat another time thereafter. As discussed in greater detail below, actsof the process 400 may be executed repeatedly and, in some examples,indefinitely.

At act 404, the system controller 110 controls one or more of the powermodules 106 to provide power to the output 108. Act 404 may besubstantially similar to act 304. The system controller 110 may controlfewer than all of the power modules 106 to provide power to the output108, or may control all of the power modules 106 to provide power to theoutput 108. For example, the system controller 110 may control all ofthe power modules 106 to provide power to the output 108 when theprocess 400 and act 404 are first executed before a more efficientsubset of the power modules 106 is identified, if such a subset is soidentified, as discussed in greater detail below. Controlling the one ormore of the power modules 106 to provide power to the output 108 mayinclude the system controller 110 sending an activation signal to eachof the one or more power modules 106 (also referred to herein as“activating” the one or more power modules 106), similar to act 304.

At act 406, one or more module controllers 216 of respective powermodules 106 monitor a respective module output 210, and the systemcontroller 110 monitors the load 114. The system controller 110 maymonitor the load 114 in a manner similar to the manner discussed abovewith respect to act 306. A module controller 216 may similarly monitorthe load 114 by determining module load information indicative of outputpower provided at the module output 210 (including, for example, voltageand/or current information), and determining power requirements of theload 114. In another example, module load information may includeinformation indicative of power drawn by the load 114 where power may ormay not be provided at the module output 210. The module controller 216may determine the module load information based on information sensed bythe module sensors 218, including information sensed at the moduleoutput 210. For example, the module sensors 218 may include one or morecurrent or voltage sensors configured to sense a current and/or voltageat the module output 210. The module sensors 218 provide the module loadinformation to the module controller 216. In some examples, each modulecontroller 216 may be communicatively coupled to one or more sensors,such as the system sensors 112, configured to determine load informationindicative of a power drawn at the output 108 in addition to the modulesensors 218. Accordingly, each module controller 216 may determine loadinformation indicative of a power drawn at a respective module output210 and/or at the output 108 of the power system 100.

In some examples, a respective module controller 216 of each of thepower modules 106 monitors a respective module output 210 at act 406. Inother examples, only module controllers 216 corresponding to activepower modules 106 monitor a respective module output 210. In otherexamples, only module controllers 216 corresponding to deactivated powermodules 106 monitor a respective module output 210. In other examples, acombination of module controllers 216 corresponding to active anddeactivated power modules 106 monitor a respective module output 210. Invarious examples, load information determined by a module controller 216may vary based on whether the module controller 216 corresponds to anactive power module 106. For example, if the module controller 216corresponds to an inactive power module 106 having an inactive inverter208, the module sensors 218 may provide voltage information indicativeof a voltage at the module output 210 to the module controller 216, butthe module sensors 218 may not provide output current information to themodule controller 216. In another example, if the module controller 216corresponds to an active power module 106 having an active inverter 208,the module sensors 218 may provide voltage information indicative of avoltage at the module output 210 and current information indicative of acurrent provided by the inverter 208 to the module controller 216. Inother examples, the module controller 216 may determine other loadinformation or no load information based on a mode of operation.

At act 408, each module controller 216 monitoring the load 114determines whether additional power modules should be activated. If anoverload condition is determined to exist by a respective modulecontroller 216, then the module controller 216 may determine thatadditional power modules should be activated. As discussed above, anoverload condition may be detected where the output power requirementsof the load 114 increase beyond the output power capacity of the powermodules 106 that are providing output power, for example, or whereactivating additional power modules 106 would be desirable even if theincreased output power requirements are capable of being met by thecurrently active power modules 106. In one example, detecting anoverload condition may include the module controller 216 determining,based on current information received from the module sensors 218, thatan output current provided by the inverter 208 is outside of a range ofacceptable current values (for example, indicating an overcurrentcondition). In another example, detecting the overload condition mayinclude the module controller 216 determining, based on voltageinformation received from the module sensors 218, that an output voltageprovided at the output 108 is outside of a range of acceptable voltagevalues (for example, indicating a voltage sag condition). In anotherexample, detecting the overload condition may include the modulecontroller 216 determining, based on power information received from themodule sensors 218 (including, for example, current and/or voltageinformation), that an output voltage provided at the output 108 isoutside of a range of acceptable voltage values (for example, indicatinga voltage sag condition).

If the module controller 216 monitoring the load 114 determines thatadditional power modules 106 should not be activated (408 NO), then theprocess 400 returns to act 406. The module controller 216 continuesmonitoring the load 114, and acts 406 and 408 are repeated until adetermination is made that additional power modules 106 should beactivated. For example, if the module controller 216 detects an overloadcondition and determines that additional power modules 106 should beactivated (408 YES), then the process 400 continues to act 410.

At act 410, each active module controller 216 that determines thatadditional power modules 106 should be activated (408 YES) activates anyof the power modules 106 that are deactivated. Deactivated power modulesmay include those of the power modules 106 that are not controlled toprovide output power at the output 108 at act 404. In some examples,activating the deactivated power modules 106 may include sending, byeach active module controller 216, an activation signal to all otherpower modules 106, or a subset of the power modules 106, such as thoseof the power modules 106 that are deactivated. For example, the signalsent to the system controller 110 may include a request or instructionfor the system controller 110 to send an activation signal to all of thepower modules 106, or those of the power modules 106 that aredeactivated. In other examples, each module controller 216 of adeactivated power module 106 may activate itself at act 410, and may ormay not send an activation signal to the other power modules 106. Onceeach of the power modules 106 has been activated, the power modules 106collectively provide power to the output 108 at a first efficiency.

At act 412, the system controller 110 selects at least one power moduleof the power modules 106 to maintain in an active state based on theload information received at act 406. Act 412 may be substantiallysimilar to act 312. As discussed above, selecting the at least one powermodule may include selecting fewer than all of the power modules 106 toprovide output power to the output 108 at an efficiency greater than ifall of the power modules 106 were to provide output power to the output108.

At act 414, the system controller 110 deactivates those of the powermodules 106 that are not remaining active. Deactivating the powermodules 106 may include sending, by the system controller 110, adeactivation signal to each of the power modules 106 not remainingactive, or may include de-asserting an activation signal that the systemcontroller 110 sent to the power modules 106 at act 310. The powermodules 106 discontinue providing output power to the output 108responsive to receiving the deactivation signal. A respective modulecontroller 216 may receive the deactivation signal and, in responsethereto, control components thereof, such as the switches 220-224, todiscontinue providing power to the module output 210. For example, themodule controller 216 may control the inverter switches 222 todiscontinue providing output power at the module output 210 (alsoreferred to herein as “deactivating the inverter 208”), which mayinclude controlling one or more of the inverter switches 222 to be in anopen and non-conducting position such that the DC bus 206 iselectrically disconnected from the module output 210. In other examples,deactivating the power modules 106 may include the system controller 110directly controlling components of the power modules 106, such as one ormore of the switches 220-224, to discontinue providing output power atthe module output 210.

The process 400 then returns to act 404. At act 404, the systemcontroller 110 controls those of the power modules 106 selected toremain active at act 412 to provide output power at the output 108. Act404 is substantially similar to act 304.

Accordingly, the processes 300, 400 may be executed to select a group ofone or more of the power modules 106 to maintain in an active state inwhich power is provided to the output 108. Remaining power modules maybe deactivated such that power is not provided to the output 108.Providing power to the output 108 with fewer than all of the powermodules 106 may increase an efficiency of the power system 100 ascompared to providing power to the output 108 with all of the powermodules 106.

If power requirements of the load 114 change after selecting the groupof one or more of the power modules 106 to maintain in an active state(for example, increase), additional power modules may be activated. Inthe process 300, the system controller 110 monitors power information(including, for example, current and voltage information) with thesystem sensors 112 to determine if additional power modules should beactivated. In the process 400, a respective module controller 216 of oneor more of the power modules 106 monitors load information with themodule sensors 218 and/or the system sensors 112 to determine ifadditional power modules should be activated. In some examples, thepower system 100 may execute only one of the processes 300, 400 at onetime. In other examples, the power system 100 may execute both of theprocesses 300, 400 simultaneously, alternately, or some combinationthereof.

As discussed above in connection with acts 308 and 408, a determinationmay be made by the system controller 110 and/or a module controller 216as to whether to activate additional power modules. In some examples,including examples provided above, additional power modules may beactivated responsive to determining that the output power requirementsof the load 114 exceed an output power capacity of the currently activepower modules 106. In other examples, additional power modules may beactivated responsive to other conditions in addition to, or in lieu of,determining that the output power requirements of the load 114 exceed anoutput power capacity of the currently active power modules 106. Suchconditions may be referred to herein as “wake-up conditions,” and mayinclude the output power requirements of the load 114 exceeding anoutput power capacity of the currently active power modules 106.

Other wake-up conditions may include the output power requirements ofthe load 114 changing by more than a threshold amount after the group ofthe power modules 106 to provide power to the load 114 is selected. Thethreshold amount may be a relative value (for example, a 10% change inoutput power requirements) or an absolute value (for example, a 500 Wchange in output power requirements). Multiple thresholds may beimplemented. For example, a wake-up condition may be satisfied if theoutput power requirements of the load 114 increase by more than a firstthreshold amount or decrease more than a second threshold amount, whichmay be different than the first threshold amount.

Other wake-up conditions may include a threshold amount of time havingelapsed since the group of the power modules 106 to provide power to theload 114 was selected. The threshold amount of time may vary based on anumber of the power modules 106 that are active.

Other wake-up conditions may be based in part on power received at thepower input 102. For example, if power at the power input 102 becomesacceptable after being unacceptable, or becomes unacceptable after beingacceptable, the wake-up condition may be satisfied. In another example,a wake-up condition may be based on anomalies in the power received atthe power input 102 including, for example, certain power transientconditions.

Other wake-up conditions may be based in part on power stored in theenergy storage devices 104. For example, a wake-up condition may besatisfied if the power system 100 is operating in a back-up mode ofoperation and one or more of the energy storage devices 104 becomesdepleted of stored energy. In another example, a wake-up condition maybe satisfied if the power system 100 is operating in a normal mode ofoperation and is charging the energy storage devices 104, and one ormore of the energy storage devices 104 becomes fully charged.

Other wake-up conditions may be based on a status condition of the powersystem 100. For example, a wake-up condition may be satisfied if anyanomalies or error conditions are detected. Such error conditions mayinclude, for example, a component failure, a parameter (for example,temperature) falling outside or inside a range of values, and so forth.

In various examples, other wake-up conditions may be implemented.Furthermore, one or more of the foregoing wake-up conditions may beimplemented in combination with one another. Accordingly, no limitationis implied by the example wake-up conditions identified above.

As discussed above, the system controller 110 may identify a group ofone or more of the power modules 106 to maintain in an active mode ofoperation. In some examples, the system controller 110 identifies agroup of one or more of the power modules 106 that provides power to theoutput 108 at a highest efficiency. For example, the system controller110 may determine, based on stored efficiency information, an efficiencyof the power system 100 for every combination of the power modules 106being in an active state and select the most efficient group of thepower modules 106.

In other examples, the system controller 110 may select the group of thepower modules 106 to maintain in an active state based on one or moreadditional or alternate parameters. For example, the system controller110 may consider a temperature of one or more components of the powersystem 100 in selecting the group of the power modules 106 to maintainin an active state. In one example, the system controller 110 may selecta highest-efficiency group of the power modules 106 where components ofthe power system 100 are within a first range of temperature values, butmay select a different group of the power modules 106 that does notprovide a highest efficiency where components of the power system 100are within a second range of temperature values. If the power system 100is too hot, for example, it may be undesirable to prioritize efficiencyover other concerns. Furthermore, in various examples, the systemcontroller 110 may have access to stored efficiency information for thepower modules 106 indicating an efficiency-versus-load for varioustemperature values (for example, stored in the storage 116), such thatthe system controller 110 may determine an efficiency of each of thepower modules 106 operating at a certain load and at a certaintemperature.

In another example, the system controller 110 may select a group of thepower modules 106 to maintain in an active state based on additionalparameters. For example, the system controller 110 may determine thatmaintaining a first group of the power modules 106 in an active state ismore efficient than maintaining a second group of the power modules 106in an active state. The system controller 110 may nonetheless maintainthe second group of the power modules 106 in the active state ratherthan the first group based on considerations other than, or in additionto, efficiency. For example, the first and second group may each includetwo power modules, but the modules of the first group of power modulesmay have consumed more of their operating lifetimes than those of thesecond group. The system controller 110 may select the second group tomaintain in an active state, such that the operating lifetimes of thefirst and second groups are balanced. In this example, however, if theefficiency of the first group exceeds the efficiency of the second groupby more than a certain amount, the system controller 110 may nonethelessselect the first group to maintain in an active state if efficiencyconcerns outweigh an interest in balancing operating lifetimes. It is tobe appreciated that other examples are within the scope of thedisclosure, and that efficiency-increasing concerns or interests may bebalanced with other benefits.

In some examples, the power system 100 may be configured to receive ACpower from the power input 102. However, in other examples, the powersystem 100 may be configured to receive DC power. One or more of thepower modules 106 may be configured to receive DC power at a respectivemodule input 202 in addition to, or in lieu of, AC power. In theseexamples, the rectifier 204 may be replaced by a component configured toreceive and/or filter DC power from the module input 202 (for example, aDC/DC converter), and provide output power to the DC bus 206. In otherexamples, the rectifier 204 may be removed without being replaced, suchthat the module input 202 is coupled directly to the DC bus 206.Similarly, the inverter 208 may be removed and may be replaced by adifferent component, such as a DC/DC converter, a switching device, or asimilar component. In still other examples, the rectifier 204 and/or theinverter 208 may be replaced or supplemented by components configured tooperate in connection with either DC or AC power, such that the powermodule 106 is capable of receiving either AC or DC power at the moduleinput 202, and is capable of outputting either AC or DC power at themodule output 210. In some examples, the power system 100 may beconfigured to receive AC power at the power input 102, but may beconfigured to provide DC power, rather than AC power, at the moduleoutput 210. In these examples, the inverter 208 may be replaced by analternate component configured to output DC power. Accordingly, it is tobe appreciated that the principles of the disclosure are not limited toany particular type of input or output power.

In some examples, a range of permissible loads for each of the powermodules 106 may vary based on the load 114. For example, the powermodules 106 may be capable of operating between 20% and 95% of a ratedload where the load 114 is a first type of load (for example, anon-critical load). However, the power modules 106 may be capable ofoperating only between 20% and 75% of a rated load where the load 114 isa second type of load (for example, a critical load). Different loadsmay be categorized into various categories, each of which may berestricted to a specified range of a rated load. In some examples, eachof the power modules 106 may have a different permissible range. Forexample, one or more of the power modules 106 may be of a differenttype, or have a different rating, than others of the power modules 106.

As discussed above, deactivating a power module 106 may includecontrolling, by a respective module controller 216, respective inverterswitches 222 to be in an open and non-conducting position such that theDC bus 206 and the bus capacitors 226 are electrically disconnected fromthe module output 210. In various examples, the rectifier 204 and/or theDC/DC converter 212 may remain operational while the power module 106 isdeactivated such that the bus capacitors 226 remain at an activeoperating voltage. In some examples, the rectifier 204 and/or the DC/DCconverter 212 may not remain operational while the power module 106 isdeactivated. Whether the rectifier 204 and/or the DC/DC converter 212remain operational may depend on a type or operating requirements of theload 114. For example, if the load 114 is less sensitive tointerruptions in power provision, the rectifier 204 and/or the DC/DCconverter 212 may not maintain the bus capacitors 226 at an activeoperating voltage in some examples. Conversely, if the load 114 issensitive to interruptions in power provision, the bus capacitors 226may be maintained at an active operating voltage such that the powermodule 106 is capable of quickly transitioning to providing output powervia the inverter 208.

Although certain examples may be implemented in connection with modularuninterruptible power supplies, it is to be appreciated that otherexamples may be implemented in connection with other devices. In someexamples, principles of the disclosure may be practiced in connectionwith a non-modular power device having a fixed number ofpower-conditioning components in lieu of the power modules 106. Inanother example, principles of the disclosure may be implemented toselect a most efficient group of components other than power modules tomaintain in an active state, such as one or more energy storage devicescapable of being selectively activated or deactivated to dischargestored energy. In some examples, principles of the disclosure may beimplemented in connection with a device other than an uninterruptiblepower supply.

Accordingly, examples discussed herein enable an efficiency of a modularUPS to be increased by selectively activating power modules in a UPS.Load information is determined by a system controller and/or a modulecontroller in one or more power modules to identify output powerrequirements of a load. A determination may be made by the systemcontroller as to which combination of power modules can most efficientlysatisfy the output power requirements. The identified combination ofpower modules may be instructed by the system controller to maintain anactive state in which output power is provided to the load. Theremaining power modules may be instructed to enter a deactivated statein which the power modules do not provide output power to a load. Forexample, a deactivated power module may deactivate its inverter suchthat the output of the power module is disconnected from a power sourceof the power module.

The output power requirements of the load may change over time. Thesystem and/or module controllers may repeatedly re-evaluate whether awake-up condition is met, which may be based on the output powerrequirements. The wake-up condition may be that the output powerrequirements exceed the power rating of the combination of activatedpower modules, for example, or that the output power requirements havechanged above a threshold amount. If the wake-up condition is met, powermodules that were not already active (that is, the deactivated powermodules) may be activated by the system and/or module controllers toprovide output power to the load. The system controller again determinesa combination of power modules that can most efficiently satisfy theoutput power requirements of the load, and deactivates the remainingpower modules.

Having thus described several aspects of at least one embodiment, it isto be appreciated various alterations, modifications, and improvementswill readily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be part of, and withinthe spirit and scope of, this disclosure. Accordingly, the foregoingdescription and drawings are by way of example only.

What is claimed is:
 1. A power system comprising: an input to receiveinput power; an output to provide output power to a load; a sensorconfigured to provide load information indicative of power drawn by theload; a plurality of power modules, each power module of the pluralityof power modules having a power module input configured to be coupled tothe input, a power module output configured to be coupled to the output,an AC/DC converter coupled to the power module input, a DC/AC invertercoupled to the power module output, a power bus coupled to the AC/DCconverter and the DC/AC inverter, a module sensor configured todetermine module load information indicative of power provided at arespective power module output, and a module controller configured toreceive the module load information from the module sensor, wherein eachactivated module controller is configured to detect, based on the moduleload information, an overload condition, and provide an activationsignal to at least one other power module of the plurality of powermodules based on detecting the overload condition; and a systemcontroller coupled to the plurality of power modules and to the sensor,the system controller being configured to: control the plurality ofpower modules to provide power to the output; receive the loadinformation from the sensor; select, based on the load information, atleast one power module of the plurality of power modules to maintain inan active state to provide power to the output; and deactivate eachpower module of the plurality of power modules other than the at leastone power module based on selecting the at least one power module tomaintain in the active state.
 2. The power system of claim 1, whereineach activated module controller is communicatively coupled to thesystem controller and is configured to: receive, from the systemcontroller, a deactivation signal or an activation signal; control therespective power module to continue providing module output powerresponsive to receiving the activation signal; and control therespective power module to deactivate and discontinue providing moduleoutput power responsive to receiving the deactivation signal.
 3. Thepower system of claim 2, wherein the system controller is configured to:select a first group of one or more power modules to maintain in anactive state responsive to the overload condition; provide theactivation signal to each power module in the first group of one or morepower modules; select a second group of one or more power modules todeactivate responsive to the overload condition; and provide thedeactivation signal to each power module in the second group of one ormore power modules.
 4. The power system of claim 3, wherein selectingthe first group of one or more power modules to maintain in the activestate includes identifying a most efficient group of one or more powermodules to satisfy the overload condition.
 5. The power system of claim1, wherein the system controller is configured to: detect, based on theload information, an overload condition; and activate each deactivatedpower module of the plurality of power modules to provide module outputpower based on detecting the overload condition.
 6. The power system ofclaim 5, wherein the system controller is configured to: select a firstgroup of one or more power modules to maintain in an active stateresponsive to the overload condition; provide the activation signal toeach power module in the first group of one or more power modules;select a second group of one or more power modules to deactivateresponsive to the overload condition; and provide the deactivationsignal to each power module in the second group of one or more powermodules.
 7. The power system of claim 6, wherein selecting the firstgroup of one or more power modules to maintain in the active stateincludes identifying a most efficient group of one or more power modulesto satisfy the overload condition.
 8. The power system of claim 1,wherein deactivating each power module includes sending a deactivationsignal to each power module.
 9. The power system of claim 8, whereineach power module includes a respective switch configured to controloutput electrical power, and wherein each power module is configured todeactivate the switch responsive to receiving the deactivation signal.10. The power system of claim 9, wherein each DC/AC inverter includesthe respective switch.
 11. The power system of claim 1, wherein eachDC/AC inverter is configured to: draw bus power from the power bus at anactive operating voltage; convert the bus power to the output power; andprovide the output power to the output.
 12. The power system of claim11, wherein each power module is configured to control a respectiveAC/DC converter to maintain the power bus at the active operatingvoltage level while the respective power module is deactivated.
 13. Thepower system of claim 1, wherein each power module is configured tocontrol a respective DC/AC inverter to be deactivated while therespective power module is deactivated.
 14. A power module in a powersystem providing power to a load, the power module comprising: a moduleinput configured to receive input power; a module output configured toprovide output power to the load; at least one module sensor configuredto provide load information indicative of the output power provided atthe module output; an AC/DC converter coupled to the module input; aDC/AC inverter coupled to the module output; a power bus coupled to theAC/DC converter and the DC/AC inverter; and a module controller coupledto the at least one module sensor and configured to: receive the loadinformation from the at least one module sensor; determine, based on theload information, that an overload condition exists; provide, responsiveto determining that the overload condition exists, an activation signalto at least one other power module instructing the at least one otherpower module to provide output power to the load; determine that thepower module is to be deactivated; and deactivate the power module todiscontinue providing the output power to the module output, wherein themodule controller is coupled to a system controller coupled to the atleast one other power module, and wherein determining that the powermodule is to be deactivated includes receiving a deactivation signalfrom the system controller.
 15. The power module of claim 14, whereindetermining that the overload condition exists includes determining,based on the load information, that a power rating of the load exceeds apower level of power provided to the load.
 16. The power module of claim14, wherein the module controller is further configured to: receive anactivation signal from the at least one other power module; andtransition from deactive to active responsive to receiving theactivation signal from the at least one other power module.
 17. Thepower module of claim 14, wherein the DC/AC inverter includes at leastone switching device to control the output power, and whereindeactivating the power module includes deactivating the at least oneswitch.
 18. The power module of claim 14, wherein the DC/AC inverter isconfigured to: draw bus power from the power bus at an active operatingvoltage; convert the bus power to the output power; and provide theoutput power to the output.
 19. The power module of claim 18, whereinthe module controller is configured to control a respective AC/DCconverter to maintain the power bus at the active operating voltagelevel while the power module is deactivated.
 20. A non-transitorycomputer-readable medium storing thereon sequences ofcomputer-executable instructions for controlling a power module having amodule input configured to receive input power, a module outputconfigured to provide power to a load, at least one load sensorconfigured to provide load information, an AC/DC converter coupled tothe module input, a DC/AC inverter coupled to the module output, and apower bus coupled to the AC/DC converter and the DC/AC inverter, thepower module being coupled to a system controller coupled to at leastone other power module, the sequences of computer-executableinstructions including instructions that instruct at least one processorto: control the power module to provide power to the load; receive loadinformation from the at least one load sensor; determine, based on theload information, whether an overload condition exists; provide,responsive to determining that the overload condition exists, anactivation signal to at least one other power module instructing the atleast one other power module to provide output power to the load;determine that the power module is to be deactivated, whereindetermining that the power module is to be deactivated includesreceiving a deactivation signal from the system controller; anddeactivate the power module to discontinue providing the output power tothe module output.